mvc 文件下载

public class DownLoadHelper
    {

        /// <summary>
        /// WriteFile实现下载--测试通过
        /// </summary>
        /// <param name="filePath">文件路径</param>
        public static void  DownLoadWithWriteFile(string filePath)
        {
            string fileName = Path.GetFileName(filePath);//客户端保存的文件名
            FileInfo fileInfo = new FileInfo(filePath);
            HttpContext.Current.Response.Clear();
            HttpContext.Current.Response.ClearContent();
            HttpContext.Current.Response.ClearHeaders();
            HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName);
            HttpContext.Current.Response.AddHeader("Content-Length", fileInfo.Length.ToString());
            HttpContext.Current.Response.AddHeader("Content-Transfer-Encoding", "binary");
            HttpContext.Current.Response.ContentType = "application/octet-stream";
            HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.GetEncoding("gb2312");
            HttpContext.Current.Response.WriteFile(fileInfo.FullName);
            HttpContext.Current.Response.Flush();
            HttpContext.Current.Response.End();
        }
        /// <summary>
        /// WriteFile分块下载--测试通过
        /// </summary>
        /// <param name="filePath">文件路径</param>
        public static void DownLoadWithWriteFileByStep(string filePath)
        {
            string fileName = Path.GetFileName(filePath);//客户端保存的文件名
            System.IO.FileInfo fileInfo = new System.IO.FileInfo(filePath);
            if (fileInfo.Exists)
            {
                const long ChunkSize = ;//100K 每次读取文件，只读取100K，这样可以缓解服务器的压力
                byte[] buffer = new byte[ChunkSize];
                HttpContext.Current.Response.Clear();
                System.IO.FileStream iStream = System.IO.File.OpenRead(filePath);
                long dataLengthToRead = iStream.Length;//获取下载的文件总大小
                HttpContext.Current.Response.ContentType = "application/octet-stream";
                HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName));
                while (dataLengthToRead >  && HttpContext.Current.Response.IsClientConnected)
                {
                    int lengthRead = iStream.Read(buffer, , Convert.ToInt32(ChunkSize));//读取的大小
                    HttpContext.Current.Response.OutputStream.Write(buffer, , lengthRead);
                    HttpContext.Current.Response.Flush();
                    dataLengthToRead = dataLengthToRead - lengthRead;
                }
                HttpContext.Current.Response.Close();
            }
        }
        /// <summary>
        /// 流方式下载--测试通过
        /// </summary>
        /// <param name="filePath">文件路径</param>
        public static void DownLoadWithStream(string filePath)
        {
            string fileName = Path.GetFileName(filePath);//客户端保存的文件名
            //以字符流的形式下载文件
            FileStream fs = new FileStream(filePath, FileMode.Open);
            byte[] bytes = new byte[(int)fs.Length];
            fs.Read(bytes, , bytes.Length);
            fs.Close();
            HttpContext.Current.Response.ContentType = "application/octet-stream";
            //通知浏览器下载文件而不是打开
            HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment;  filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));
            HttpContext.Current.Response.BinaryWrite(bytes);
            HttpContext.Current.Response.Flush();
            HttpContext.Current.Response.End();
        }
        /// <summary>
        /// TransmitFile实现下载--测试通过
        /// </summary>
        /// <param name="filePath">文件路径</param>
        public static void DownLoadWithTransmitFile(string filePath)
        {
            string fileName = Path.GetFileName(filePath);//客户端保存的文件名
            /*
         微软为Response对象提供了一个新的方法TransmitFile来解决使用Response.BinaryWrite
         下载超过400mb的文件时导致Aspnet_wp.exe进程回收而无法成功下载的问题。
         */
            HttpContext.Current.Response.ContentType = "application/x-zip-compressed";
            HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment;filename="+ HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));
            HttpContext.Current.Response.TransmitFile(filePath);
        }
    }
调用方法：

public void DownMap(string LinkUrl)
{
string filePath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "DownLoadSource\\1.txt");
DownLoadHelper.DownLoadWithTransmitFile(filePath);
}
前端:

function download(linkUrl) {
            window.location.href = "/Home/DownMap?LinkUrl=" + linkUrl;
        }